Bounties of up to $15,000 will be paid for remote code execution (RCE) vulnerabilities in Edge on the Insider builds. Insider is Microsoft's preview program which issues preliminary code to a large pool of volunteers.

RCE vulnerabilities are considered among the most dangerous, because by definition they let attackers run malicious code on a compromised device.

The latest Edge bounty will run from today through May 15, 2017, considerably longer than 2015's brief two-month stretch for Spartan/Edge.

Although Microsoft long resisted joining vendors that paid security researchers for their discoveries -- believing it was enough to credit those who turned in flaws -- the company rethought its stance and offered its first bounties in mid-2013 during the development of Internet Explorer 11 (IE11). Since then it has run several bounty programs, some of which have had hard stop dates and others that remained open-ended.

Because the new bounties will be paid for bugs identified in an under-construction browser, Microsoft warned researchers that they may end up reporting one that the company's engineers already know about, and are working to fix.

"In the event this occurs, as recognition for the real effort put into finding these vulnerabilities, a payment of up to $1,500 USD will be made to the first external researcher who reports the issue," wrote Jason Shirk, a principal security strategist, in a post to a company blog.